From The Collaborative International Dictionary of English v.0.48:
Pest \Pest\, n. [L. pestis: cf. F. peste.]
1. A fatal epidemic disease; a pestilence; specif., the
plague.
[1913 Webster]
England's sufferings by that scourge, the pest.
--Cowper.
[1913 Webster]
2. Anything which resembles a pest; one who, or that which,
is troublesome, noxious, mischievous, or destructive; a
nuisance. "A pest and public enemy." --South.
[1913 Webster]